Instruments 10 12 14 16 VOLTS 07/01/2003 f610666 09/09/2004 f610530a Miles Fig. 3.7, Voltmeter started or when electrical devices in the vehicle are being used. Fig. 3.5, Speedometer (U.S. version) If the voltmeter shows an undercharged or over- charged condition for an extended period, have the charging system and batteries checked at a repair facility. On a vehicle equipped with a battery isolator system, the voltmeter measures the average voltage of all the batteries when the engine is running. When the en- gine is stopped, the voltmeter shows only the iso- lated battery voltage and does not indicate the volt- age of the engine-starting batteries.
Optional Instruments Optional instruments are not found on every vehicle. They are listed here in alphabetical order, to make the information easier to find. Air Restriction Gauge 05/11/2001 f610532 The air intake restriction gauge measures the vacuum on the engine side of the air cleaner. On standard installations, it is mounted on the air intake duct in the engine compartment. See Fig. 3.8 . Fig. 3.6, Tachometer and the battery voltage when the engine is stopped. By monitoring the voltmeter, the driver can stay aware of potential battery charging problems and have them fixed before the batteries discharge enough to create starting difficulties.
As an option for easier viewing, an air intake restric- tion gauge may be located under the lightbar. See Fig. 3.9 . The voltmeter will normally show approximately 13.7 to 14.1 volts when the engine is running. The voltage of a fully charged battery is 12.7 to 12.8 volts when the engine is stopped. A completely discharged bat- tery will produce only about 12.0 volts. The voltmeter will indicate lower voltage as the vehicle is being NOTE: Rain or snow can wet the air filter, caus- ing a temporarily higher than normal reading. Air intake restriction vacuum is measured in inches of water (inH 2 O).
For vehicles equipped with a graduated indicator or a restriction gauge on the dash, check the gauge with the engine off. If the air 3.6